The surgeon gasped when he opened up his patient and saw what was in the man's spine. It was a huge mass, filling the entire part of his lower spinal column.
"The entire thing was filled with bloody tissue and, as I started to take pieces, it started to bleed," said Dr John Chi, the director of Neurosurgical Spine Cancer at Brigham and Women's Hospital in Boston.
"It was stuck to everything around it. I had never seen anything like it."
Tests showed that the mass was made up of abnormal, primitive cells and that it was growing very aggressively. Then came the real shocker: The cells did not come from the patient, Mr Jim Gass - they were someone else's cells.
Mr Gass, it turned out, had undergone stem cell therapy at clinics in Mexico, China and Argentina, paying tens of thousands of dollars each time for injections in a desperate attempt to recover from a stroke that he had suffered in 2009.
Including travel, the total cost had come to nearly US$300,000 (S$405,000).
A growing number of clinics, often in places such as Russia or China, but also in Europe and elsewhere, say on websites that they can treat, even cure, diseases such as muscular dystrophy, Alzheimer's, Parkinson's and spinal cord injury, as well as strokes.
This is done by injecting patients with stem cells that, in theory, could develop into a missing nerve, a muscle or other cells and repair damage from an illness or injury.
Reports by injured athletes of seemingly miraculous results have contributed to rising interest among desperate patients.
Estimates are that tens of thousands of patients around the world have had such treatments and that the industry is worth hundreds of millions of dollars.
The clinics, which are unregulated, have websites with glowing testimonials from patients, some of which, Mr Gass' sister-in-law discovered, have financial interests in the clinics. They often claim to be doing clinical trials, giving a veneer of legitimacy to their work.
Academic researchers say stem cells hold enormous promise, but they are proceeding cautiously with clinical trials because stem cells divide rapidly and can form tumours in laboratory animals.
In lab studies, stem cells can also quickly accumulate mutations like those in cancer cells.
While there have been reports in medical literature of patients who developed tumours after stem cell injections, few have been as open as Mr Gass, 66, about their quest for a cure, the money they paid and the tragic consequences.
FIRST SIGNS OF TROUBLE
I felt pain when I would lie down, like I was lying on a tumour. I started to lose my ability to walk, and I fell down a lot.
MR JIM GASS, on what happened after he had foetal cells injected into him.
After his stroke, Mr Gass - who stays in San Diego and was formerly chief legal counsel for Sylvania - still lived independently, even though his left arm was useless and his left leg was weak.
Now, however, with the foreign body in his spine, he is paralysed from the neck down, except for his right arm. He needs a hoist to move from his bed to a wheelchair.
His doctors do not know how to stop the tumour from growing. They wrote about his case in a letter published in the New England Journal of Medicine.
Experts who have written articles in medical and scientific journals bemoaning "stem cell tourism" said this case could make a difference.
"We scientists and clinicians say: 'Don't do this'," said Dr Jaime Imitola - a neurologist and stem cell researcher at Ohio State University's Wexner Medical Centre - who has written about the dangers of stem cell tourism.
However, he said, their warnings often do not resonate.
He said Mr Gass "puts a human face to a tragedy". Patients might see what happened to Mr Gass "and say, 'Oh my God, that could be me".
"This is a really cautionary tale," said Professor Timothy Caulfield, the research director of the Health Law Institute at the University of Alberta, who wrote a recent commentary on stem cell clinics.
Mr Gass' problems began on May 10, 2009, when he woke up with a terrible headache. He tried to get out of bed and fell to the floor, unable to move. He had suffered a stroke. Two years later, he was able to walk only with a leg brace and a cane.
"I began doing research on the Internet," he said. He was particularly struck by the tale of former football star and professional golfer John Brodie, who had a stroke, received stem cell therapy in Russia and returned to playing golf again.
So Mr Gass contacted Stemedica, a company that had been involved with the clinic, and learnt about a programme in Kazakhstan. When he baulked at going there, the Russian clinic referred him to one in Mexico. That was the start of his odyssey.
His doctors and his sister-in-law, Ms Ruth Gass, tried to dissuade him. She called the clinics and demanded evidence that their treatments worked.
Some of the clinics hung up, saying that they would not talk to a terrified relative, she said. Websites often had data but it did not hold up to basic analysis, she said, and when the data was published, it appeared in vanity journals. Other clinics simply told her that "people get dramatically better".
She raged against the clinics, telling them: "You ought to be ashamed for charging US$40,000 a shot. You prey on people like my brother-in-law, who is desperate for help."
Then came her kicker: "I said, 'If what you are saying is true, you should get the Nobel Prize. If not, you ought to go to hell. Shame on you.' "
But Mr Gass was undeterred. He was willing to spend the money and go anywhere. What did he have to lose? The worst that could happen, he thought, was that he would have no improvement.
He went from clinic to clinic, ending up back in Mexico for an injection of foetal cells shipped from Russia. Six months later, his walking improved. But the improvement did not last long, so he had another injection. Then something disturbing happened.
He said: "I felt pain when I would lie down, like I was lying on a tumour. I started to lose my ability to walk, and I fell down a lot."
He was in Thailand at the time, a place he likes to visit. Doctors at a hospital there tried to do a spinal tap, but told him that something was wrong. There seemed to be no spinal fluid.
He returned to the United States, to Boston, where he had spent most of his life, and where his brother and sister-in-law lived, and asked the doctors at Brigham and Women's Hospital for help.
They did a magnetic resonance imaging (MRI) scan of his spine and were aghast when they saw the image.
"The entire lower portion of his spinal column was filled with a mass," said Dr Aaron Berkowitz, the director of the hospital's Global Neurology Programme.
The only option was to operate.
But though the doctors now knew what the mass was, they were left with another problem: How could they stop it from growing?
If it had been an infection, they could have used antibiotics. If it had been cancer, they could have used drugs to target it. This mass, however, was unique.
They decided to try radiation. It seemed to slow the growth a bit, perhaps even shrank the mass. But recently, Mr Gass had another scan in San Diego, and doctors told him that the mass was growing again.
Asked what he would like others to learn from his experience, he said: "Don't trust anecdotes."
His sister-in-law had a different reply: "If something sounds too good to be true, it is."
NEW YORK TIMES